Message-ID: <00000000000045d4f10581fe59a7@google.com>
Date:   Sat, 16 Feb 2019 00:05:02 -0800
From:   syzbot <syzbot+56fbe62f8c55f860fd99@...kaller.appspotmail.com>
To:     hughd@...gle.com, linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        syzkaller-bugs@...glegroups.com
Subject: KASAN: use-after-free Read in shmem_fault

Hello,

syzbot found the following crash on:

HEAD commit:    aa0c38cf39de Merge branch 'fixes' of git://git.kernel.org/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=146cadff400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ee434566c893c7b1
dashboard link: https://syzkaller.appspot.com/bug?extid=56fbe62f8c55f860fd99
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+56fbe62f8c55f860fd99@...kaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x30e0/0x4700  
kernel/locking/lockdep.c:3215
Read of size 8 at addr ffff888098eda1a0 by task syz-executor.2/16643

CPU: 0 PID: 16643 Comm: syz-executor.2 Not tainted 5.0.0-rc6+ #68
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x172/0x1f0 lib/dump_stack.c:113
  print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187
  kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
  __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
  __lock_acquire+0x30e0/0x4700 kernel/locking/lockdep.c:3215
  lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3841
  __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
  _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144
  spin_lock include/linux/spinlock.h:329 [inline]
  shmem_fault+0x5b4/0x760 mm/shmem.c:1972
  __do_fault+0x116/0x4e0 mm/memory.c:3019
  do_read_fault mm/memory.c:3430 [inline]
  do_fault mm/memory.c:3556 [inline]
  handle_pte_fault mm/memory.c:3787 [inline]
  __handle_mm_fault+0x2cbd/0x3f20 mm/memory.c:3911
  handle_mm_fault+0x43f/0xb30 mm/memory.c:3948
  faultin_page mm/gup.c:535 [inline]
  __get_user_pages+0x7b6/0x1a40 mm/gup.c:738
  populate_vma_page_range+0x20d/0x2a0 mm/gup.c:1247
  __mm_populate+0x204/0x380 mm/gup.c:1295
  mm_populate include/linux/mm.h:2388 [inline]
  vm_mmap_pgoff+0x213/0x230 mm/util.c:355
  ksys_mmap_pgoff+0xf7/0x630 mm/mmap.c:1609
  __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
  __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
  __x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91
  do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457e39
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fe43bdebc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000457e39
RDX: 0000000000000003 RSI: 0000000000b36000 RDI: 0000000020000000
RBP: 000000000073bf00 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 00007fe43bdec6d4
R13: 00000000004c3b9e R14: 00000000004d6c88 R15: 00000000ffffffff

Allocated by task 16643:
  save_stack+0x45/0xd0 mm/kasan/common.c:73
  set_track mm/kasan/common.c:85 [inline]
  __kasan_kmalloc mm/kasan/common.c:496 [inline]
  __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:469
  kasan_kmalloc mm/kasan/common.c:504 [inline]
  kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:411
  kmem_cache_alloc+0x12d/0x710 mm/slab.c:3543
  shmem_alloc_inode+0x1c/0x50 mm/shmem.c:3544
  alloc_inode+0x66/0x190 fs/inode.c:210
  new_inode_pseudo+0x19/0xf0 fs/inode.c:906
  new_inode+0x1f/0x40 fs/inode.c:935
  shmem_get_inode+0x84/0x780 mm/shmem.c:2148
  __shmem_file_setup.part.0+0x1e2/0x2b0 mm/shmem.c:3900
  __shmem_file_setup mm/shmem.c:3894 [inline]
  shmem_kernel_file_setup mm/shmem.c:3930 [inline]
  shmem_zero_setup+0xe2/0x474 mm/shmem.c:3974
  mmap_region+0x136c/0x1760 mm/mmap.c:1802
  do_mmap+0x8e2/0x1080 mm/mmap.c:1559
  do_mmap_pgoff include/linux/mm.h:2379 [inline]
  vm_mmap_pgoff+0x1c5/0x230 mm/util.c:350
  ksys_mmap_pgoff+0xf7/0x630 mm/mmap.c:1609
  __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
  __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
  __x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91
  do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 16:
  save_stack+0x45/0xd0 mm/kasan/common.c:73
  set_track mm/kasan/common.c:85 [inline]
  __kasan_slab_free+0x102/0x150 mm/kasan/common.c:458
  kasan_slab_free+0xe/0x10 mm/kasan/common.c:466
  __cache_free mm/slab.c:3487 [inline]
  kmem_cache_free+0x86/0x260 mm/slab.c:3749
  shmem_destroy_callback+0x6e/0xc0 mm/shmem.c:3555
  __rcu_reclaim kernel/rcu/rcu.h:240 [inline]
  rcu_do_batch kernel/rcu/tree.c:2452 [inline]
  invoke_rcu_callbacks kernel/rcu/tree.c:2773 [inline]
  rcu_process_callbacks+0x928/0x1390 kernel/rcu/tree.c:2754
  __do_softirq+0x266/0x95a kernel/softirq.c:292

The buggy address belongs to the object at ffff888098eda000
  which belongs to the cache shmem_inode_cache(49:syz2) of size 1184
The buggy address is located 416 bytes inside of
  1184-byte region [ffff888098eda000, ffff888098eda4a0)
The buggy address belongs to the page:
page:ffffea000263b680 count:1 mapcount:0 mapping:ffff888085ba8d80  
index:0xffff888098edaffd
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea000283a708 ffffea00029ce6c8 ffff888085ba8d80
raw: ffff888098edaffd ffff888098eda000 0000000100000001 ffff88805755e540
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff88805755e540

Memory state around the buggy address:
  ffff888098eda080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff888098eda100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff888098eda180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                ^
  ffff888098eda200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff888098eda280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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